Electronic displays are provided in many contexts to electronically render digital information to a viewer. The electronic displays receive information, and render the information through lighted cells in patterns that reflect the texts and pictures employed to convey the information.
A head-up display (HUD) allows a viewer to view not only the lighted information, but due to the transparent nature of the HUD, the view through the HUD. Thus, a viewer may be delivered information while not losing the ability to view the real world through the HUD.
HUDs are implemented in a variety of contexts, and more commonly in the vehicle. The HUD may be implemented in a variety of surfaces and windows, for example, the front windshield. Thus, when a driver/occupant is in a vehicle, content may be displayed to the driver/occupant on the front windshield accordingly.
FIG. 1 illustrates a perspective view of a sample head-up display (HUD) employing dual-image technology. Referring to FIG. 1, a HUD is implemented in a front windshield of a vehicle. The HUD allows a viewer to see the environment in front of the vehicle, with digital content being display via augmented content. For example, as shown, virtual image 101 shows an augmentation of a lane line, while virtual image 102 shows a speed of travel.
The HUD shown in FIG. 1 has been implemented employing various techniques. One such implementation has been to use two independent systems. However doing so has led to implementations that employ large amount of space. In the automotive context, where space is limited, these implementations require other componentry and design compromises.
In order to implement a dual-image HUD with a single picture generating unit (PGU), a blind wall design has been relied upon. FIG. 2 illustrates an example HUD system 200 employing a blind wall 255. The HUD system 200 shown has two distinct backlights (251 and 252). Disposed in between the backlights is the blind wall 255.
Each of the backlights is provided a unique path to reflect content, and ultimately project said content onto a HUD screen 210. As shown in FIG. 2, backlight 252 is provided with mirror 280. Conversely, backlight 251 is oriented to first reflect light off a mirror 260, then to mirror 270, and ultimately to mirror 280. After which, content sourced from backlight 251 is projected onto screen 210.
As shown in FIG. 2, light sourced from each backlight is ultimately segregated from leaking out to other paths, and as such, does not interfere with the generated image associated with the other backlight.
However, employing the blind wall 255 as shown in HUD system 200 in FIG. 2 presents additional issues. Because the blind wall has a certain thickness, this inherently creates some losses on the display surface. Further, the blind wall may effectively cancel out most interference, but some interference will still be seen via an unintended optical path.